Koji Makes Anything Taste Better. Here's How to Get Started.

A magical mold that brought two friends together, and inspired a cookbook.

June 22, 2020
Photo by Peter Larson

A strong proponent of the community that is afforded by food—its creation and consumption, virtual and not—Rich Shih, the blogger behind OurCookQuest started the hashtag #KojiBuildsCommunity about a decade ago, creating a meeting ground for cooks fueled by the common pursuit of all things koji. I fell headlong into that world, and Rich Shih, the man behind OurCookQuest, and I became pen pals. I later realized Shih was also virtual friends with a soon-to-be owner of a koji-inoculated Jewish delicatessen Jeremy Umansky. Together, they've become my onetwo-stop source for all things koji; our inboxes are littered with news of fermentation triumphs and failures—a virtual, somewhat unwieldy field notebook of sorts.

Koji, or dried rice grains cultured with aspergillus oryzae, makes any and all foods taste like hyper-version of themselves. Imagine if any and all foods could be made, naturally, to taste like hyper-real versions of themselves. That's exactly what filamentous fungus koji does: As koji spores grow (a friendly, white, fluffy mold), they break sugars and proteins down into their very basic forms, making them more readily available to our tongues.

So, what does this mean? Steaks casually seasoned with the stuff will sport a unprecedented savoriness; a prosciutto will be completely cured in a matter of months not years; and breads become intoxicatingly yeasty—all without the addition of salt, fat, sugar, or time. If that’s not the apex of culinary magic, I don’t know what is.

A few years ago, I was deep in this /koji reddit-hole, enchanted by the biology and culinary potential of… mold. Then, the conversation on koji was rather limited, the players few. When troubleshooting home charcuterie questions, I kept—again and again—being directed to blogger OurCookQuest. “He’s your guy,” fellow redditors would say. “Just PM him.”

"A physical book was just the next logical step," Umansky said to me in an interview last week. "We had to codify all we had learned—and now this book is such an easy way of sharing that information."

Join The Conversation

Top Comment:
“I made a two-hour trip to my nearest Mitsuwa the other day and saw something koji related in the refrigerator case when I was looking for abura age and miso, but I didn't really know what it was. Now I know! My question though is, I really love the flavor of broccoli (plain, unadulterated, steamed or boiled). Do I really want it to taste "yeasty" and "cheesy"? (smile)”
— Patricia F.

Koji Alchemy, Shih and Umansky’s masterful tome on the mold out just last month, will engulf you in the very best way. It’s rigorously researched, full of diagrams and photographs, and surprisingly non-intimidating, thanks to the authors’ efforts to explain the why, and not just the how. True to their spirit of knowledge-sharing , the book features recipes, guides, and musings from not just Shih and Umansky, but a multitude (over 50!) of voices. There’s author and educator Meredith Leigh on charcuterie, brewer Brian Benchek on beer, Amass research and development head Kim Wejendorp on how to turn carrot scraps into a wine (Shih's mantra—as gleaned from Matt Orlando, chef-owner of Amass—is "there’s no by-product, only another product.")

I spoke with Shih and Umansky last week about the book, and how they see koji playing into our uncertain present—and future. Our conversation has been edited and condensed for clarity.

Coral Lee: So, how did you two actually meet?

Rich Shih: We met through our love of food and cooking, driven by a common interest in sharing ideas and knowledge with a community through social media. We were both obsessively experimenting and creating with koji when few were openly sharing. As we figured out the fundamentals of how koji ticked, we independently realized that the possibilities of flavor development were endless.

Before I knew Jeremy, I was intrigued by his technique of growing koji on scallops in his TED Talk. It inspired me to reach out to him to learn more. In the same time frame, he found what I was doing with dairy to quickly yield aged cheese flavors to be interesting, and started playing with that concept. We have Cynthia Graber to thank for bringing us together. She took interest in our individual work, and suggested that we could do so much more together.

Jeremy Umansky: Cynthia was definitely the catalyst for Rich and I to start connecting on a more personal level. Rich and I had spoken a few times before she visited me in Cleveland for a Cook’s Science piece; but after her visit, we began connecting all the time. We would constantly examine each other’s work and find ways to optimize it. Rich’s cookie dough amino paste blew my mind the first time that I ate it. I knew that I had found a kindred spirit!

Aspergillus oryzae growing on rice grains. Photo by Peter Larsen

How did a book arise from this virtual friendship?

RS: There isn’t really a centralized reference on koji out there, aside from ours. Jeremy and I refer often to The Book of Miso by Shurleff and Aoyagi—which has all the information you could possibly imagine on miso—but the text is hard to parse, and the method for culturing koji in a home kitchen isn’t straightforward. Jeremy and I found ourselves and fellow experienced users bouncing ideas off of each other, sharing discoveries and research to cobble together an informal knowledge base. We also found ourselves answering the same basic questions every time a beginner would reach out to us. The book was just the logical step to codify all we had learned—and is now an easy way of sharing that information.

JU: The book needed to happen. At the end of the day, no matter how accessible we are, or anyone working with koji is, there needed to be something that people could hold in their hands. That’s exactly what we'd been seeking, and seeing that it just didn't exist in English, we decided to create it.

What is koji, and how can home cooks start playing with it?

RS: The traditional definition of koji is a specific mold (aspergillus oryzae) inoculated cooked grain (typically rice or barley) and/or soybean that’s used as a starter for Japanese ferments like shoyu, miso, sake and mirin. The modern usage of the term is more liberal as the mold can be grown on any starch substrate, and “koji” can also refer to other filamentous molds of similar functionality used across Asia (like the ones used for tempeh, Rhizopus oryzae and R. ogliosporus). The magic of koji is the array of enzymes that create unparalleled flavors when applied to pretty much any food. No other ingredient that can easily be made in a kitchen has nearly this level of impact. Very few things come close!

Shio koji is a great way for home cooks to start working with koji. It’s made by combining dried koji rice grains (available at most Asian grocers and online) with some salt and water. After a few days, the mixture becomes an enzyme packed marinade that creates amino acids with the food itself, creating an umami flavor profile that exactly matches the item at hand.

JU: It doesn’t stop at protein though. The broken-down koji starches caramelize incredibly well when cooked. Broccoli briefly marinated in shio koji and then sautéed takes on wonderful yeasty, almost cheesy flavors. It can work wonders on virtually any vegetable.

Steak dusted with koji-inoculated rice flour. Photo by Peter Larsen

Alright, I’m sold! What’s a basic guide for using shio koji, or a recipe starring it?

RS: The application of shio koji is no different than using most marinades. Just coat any piece of protein whether it be a chicken breast, pork chop, steak, fish filet or block of tofu and stick it in the fridge until you’re ready to cook it. The only thing to keep in mind is the duration—based on how tough the protein is and thickness of the cut—because the enzymes in koji can break down texture too much.

Here are some rough guidelines: Marinate a strip steak for 12 hours, chicken breast or pork chop for eight, and a white fish filet for six. When ready to cook, wipe the excess liquid off, and pat your protein dry. Sear and cook the protein as you normally would.

JU: You could even just use it as a seasoning: Drizzle a tablespoon on sautéed vegetables instead of salt.

Why is koji important for our future?

RS: What’s going on right now has given all of us a unique opportunity to think about what our priorities are. We are spending more time with our loved ones and that’s a wonderful thing. It has also, however, exposed the fragility of our food systems. Food accessibility is an issue that we've been thinking about for a while, and we have ideas on how to solve it. Koji will play a key role in our efforts to move in that direction.

JU: Koji is vital because it democratizes food and nutrition. Individual food sovereignty is the ultimate inalienable right, in our opinion. Just think about the core ingredients of a basic miso: cooked soybeans, rice, salt, and water all blended together. Without the transformative properties of koji, it would just be a lackluster, oversalted paste. With it, miso becomes highly nutritious and shelf-stable, an umami-packed base that was key to survival in ancient times. One can argue that most Eastern Asian civilizations would not be where they are today without having discovered it. Koji even produces debittering enzymes that can turn foods like lemon peels into a delicious and fantastic food with loads of bioavailable nutrients.

Koji will also make any protein more bioavailable. This means it makes tough cuts of meat tender and delicious—and that means there’s no such thing as an undesirable off-cut. It redefines how an animal is used.

Koji has unlimited potential to be applied to practically any food, especially things that can’t be sold due to excess food production or distribution issues. With it, you can make and preserve an array of products that will feed many, with base ingredients that would've otherwise gone to waste. No person should go hungry or be denied access to fresh, nutrient-dense, delicious foods.

Will koji be inoculating your cooking? Tell us about it in the comments!

See what other Food52 readers are saying.

  • Witelite
  • Patricia Fisher
    Patricia Fisher
  • BaliThai
  • jlg84
  • Karen Barnaby
    Karen Barnaby
Coral Lee is an Associate Editor at Food52. Before this, she cooked food solely for photos. Before that, she cooked food solely for customers. And before that, she shot lasers at frescoes in Herculaneum and taught yoga. When she's not writing about or making food, she's thinking about it. Her Heritage Radio Network show, "Meant to be Eaten," explores cross-cultural exchange as afforded by food. You can follow her on Instagram @meanttobeeaten.


Witelite June 28, 2020
This is so interesting... If someone was trying to reduce salt intake, could Koji be applied in lacto fermenting?? Do we know it's effects on blood pressure yet?
Patricia F. June 28, 2020
This is so intriguing and I'm going to find out more. I made a two-hour trip to my nearest Mitsuwa the other day and saw something koji related in the refrigerator case when I was looking for abura age and miso, but I didn't really know what it was. Now I know!

My question though is, I really love the flavor of broccoli (plain, unadulterated, steamed or boiled). Do I really want it to taste "yeasty" and "cheesy"? (smile)
Karen B. June 28, 2020
You will know the answer when you've tried it.
Coral L. July 14, 2020
Hey Patricia! Glad to hear you're interested in tinkering with koji. If not broccoli... maybe koji potatoes?
BaliThai June 25, 2020
What type of koji should I buy? There isn't any available locally, so I looked on Amazon. There appear to be a number of types, and I would love to know what you recommend.
Karen B. June 28, 2020
Click the link in the article where it says: (available at most Asian grocers and online).
BaliThai June 28, 2020
Thank you. I am not sure how I missed that there was a link.🤦🏼‍♀️
jlg84 June 23, 2020
I just bought koji for the first time a few weeks ago, and made shio koji to marinate a rib roast (and make a jus for same). To say the least, they were mind-blowing, so I am now determined to find more uses for koji--a copy of the book is now on its way to me!
Coral L. July 14, 2020
So glad to hear!